The effect of silane carriers on silane grafting of high-density polyethylene and properties of crosslinked products

Abstract

High-density polyethylene (HDPE) was melt-grafted with vinyl trimethoxysilane using dicumyl peroxide as initiator. Three types of ethylene copolymers were used as silane carriers, and were evaluated for their ability to assist the silane-grafting and water-crosslinking of HDPE. FTIR revealed that an increase in the amount of silane absorbed in the carriers did not help improve the silane-grafting efficiency. However, the gel and rheological results showed that those carriers promoted the rate of crosslinking and increased the density of the crosslink network. Ethylene vinyl acetate showed a stronger effect in this respect than ethylene octene and ethylene-butene copolymers. Analysis of the crosslinked materials by heat distortion temperature (HDT) test and thermogravimetric analysis (TGA) indicated a marked increase in distortion and decomposition temperatures, as well as thermal activation energy, compared to the neat HDPE. The presence of silane crosslink also resulted in a slight improvement in tensile yield stress and modulus. © 2010 Elsevier Ltd. All rights reserved.